The present application relates to a hologram recording apparatus and a hologram reconstruction apparatus.
In recent years, holographic memories serving as recording and reconstruction apparatuses capable of recording data at high density and reconstructing the data at a high transfer rate have been developed. The holographic memories utilize the thickness direction of a recording medium. When recording data, the holographic memories generate interference fringes between a reference light beam and a signal light beam according to data to be recorded in which information is two-dimensionally arranged as a page. The holographic memories three-dimensionally record the interference fringes therein at a time. When reconstructing the data, the holographic memories emit the reference light beam to the generated hologram so as to obtain a diffracted light beam. Thus, the holographic memories reconstruct the recorded data from the diffracted light beam (refer to, for example, Japanese Unexamined Patent Application Publication No. 2004-226821 and Nikkei Electronics, Jan. 17, 2005, pp. 106-114).
Holographic recording media can store a significantly large amount of recorded data compared with existing recording media. Accordingly, if a third party can easily read confidential recorded data out of the holographic recording media, leakage of a significantly large amount of confidential information or personal information could happen. That is, the risk of leakage of confidential data causing serious problems has become greater than ever before. Therefore, cipher technology that prevents a third party from reading recorded data on holographic recording media is desired. However, a cipher technology using the features of hologram recording and reconstruction has not yet been developed.